The invention relates to an apparatus for charging an energy storage unit of one or more electrically operated vehicles. To do so, the apparatus comprises at least two charging connections, wherein each of the charging connections includes a communication port for exchanging data with the vehicle connected to the charging connection.
For charging an energy storage unit of an electrically operated vehicle, a communication exchange between the vehicle and the charging apparatus is required. Within the scope of such communications, information is exchanged, for example, regarding the charge readiness of the charging apparatus, a given line connection between the vehicle and the charging apparatus, any required cooling during the charging process as well as any occurring errors. Via a so-called “duty cycle” of an oscillator, information can also be exchanged about the level of the charging current required or the maximum charging current that can be provided by the charging apparatus. Typically, the communication takes place via a pulse width modulated signal. To this end, the charging station and the vehicle have corresponding communication units.
In the case of a charging apparatus that allows for the simultaneous charging of multiple electrically operated vehicles, the aforementioned communication device must be provided for each charging connection at which a vehicle can be charged. A vehicle connected to a particular charging connection always communicates here with a communication device assigned to this charging connection.
A disadvantage of communication that is based on a pulse width modulated signal transmission is that only few specified pieces of information between the charging apparatus and the vehicles can be exchanged. This is to be remedied by digital communications, which can be based according to ISO 15188 on power-line technology. A single communication device in the charging apparatus can then communicate specifically with corresponding communication devices of a plurality of vehicles.
Since on the charging apparatuses, there will be charged both vehicles that only have a pulse width modulation-based communication device as well as those vehicles with a power-line communications-based communication device, both communication devices must be provided in the charging apparatus. The problem hereby is that pulse width modulated signals can be coupled into other communication paths via a coupling circuit of a power-line modem. Such a coupling could result in interference or malfunctions in the charging apparatus.
The object of the present invention is to provide an apparatus for charging an energy storage unit, which is structurally and/or functionally improved.
This task is solved by an apparatus according to the invention for charging an energy storage unit of one or more electrically operated vehicles. The apparatus comprises at least two charging connections. Each of the charging connections includes a communication port for exchanging data with the vehicle connected to the relevant charging connection. In addition, each of the charging connections has a power connection, by which energy from an energy network can be transmitted to the energy storage unit of the relevant vehicle.
The communication port of each of the charging connections is coupled to an assigned first communication device, which based on a pulse width modulated signal transmission is designed to communicate with a corresponding first communication device of the vehicle connected to the relevant charging connection.
Furthermore, the apparatus includes a second communication device, which is coupled via a coupling point to the communication ports of all charging connections, to communicate, based on a digital data transmission, with a corresponding second communication device of a vehicle. Because of the digital data transmission method, it is sufficient to provide only one second communication device in the apparatus. Communication with a certain charging connection and an electric vehicle coupled to it can be ensured, for example, by way of a data transmission protocol.
Lastly, the apparatus includes a compensation unit that is wired in between the coupling point and the first communication devices. The compensation unit is designed to generate a counter-phase signal to a signal that is transmitted from a transmitting first communication device to the assigned communication port or vice versa, and to apply it to the coupling point.
The compensation unit ensures that feedback from signals transmitted by the first communication device cannot adversely interfere with the second communication device. Also, the compensation unit ensures that communications between a first communication device and an assigned first communication device of a vehicle connected to a charging connection cannot be transmitted on the communication paths of the other communication ports.
The invention is based on the idea that the second communication device is coupled via a coupling network to the respective communication ports of the charging connections. In a manner known to a person skilled in the art, the coupling network comprises for every communications path at least one capacitor that connects the coupling point to the relevant communications connection of a communications path. Via this coupling, the pulse width modulated signals of a transmitting first communication device can also spread out into the lines of the communication paths to which the other first communication devices are connected. Also, the second communication device can, based on its direct coupling to the coupling point, receive the corresponding pulse-width modulated signals.
Filtering that is in principle possible has the disadvantage that a filter can always only suppress certain frequencies or frequency bands. However, a signal (generally a square-wave signal) generated by pulse width modulation (PWM) contains very many harmonic waves such that the filter would have to function in a very broad-band manner. In addition, the filter would have to be very powerful in all frequency ranges.
Due to the compensation unit, which directs a counter-phase signal of every single PWM generator of a first communication device to the coupling point, the coupling point always remains neutral. Interference can thereby not spread out. The result is broadband interference suppression. It is thereby possible without influencing to operate multiple first communication devices with a single second communication device at the same communication ports of the charging connections. The resulting advantage is that regardless of the communications technology used, charging stations can be used universally both for vehicles with a first or a second communication device. A corresponding charging apparatus can thus be provided in a cost-effective manner.
To generate a counter-phase signal, the compensation unit comprises preferably at least a first function unit for phase-shifting the signal sent out by the transmitting first communication device in operation. Such a first function unit can, for example, be realized by a power driver, as it is used in a first communication device. By being correspondingly wired in with a signal-generating unit of the first communication device, a phase shift can be effected.
In another practical design, the compensation unit comprises at least a second function unit, which replicates the electric behavior of the corresponding first communication device of the vehicle, which is connected to the charging connection, whose assigned first communication device generates the signal. The counter-phase signal can be reproduced more precisely to the signal generated by the first communication device and applied to the coupling point.
It is also purposeful if a switching element of the second function unit in operation is actuated in such a manner that its switching state corresponds to the switching state of the corresponding switching element of the corresponding first communication device. The communications behavior of the corresponding first communication device of the vehicle is hereby reproduced. Since the electrical behavior is changed by the function of the corresponding first communication device, this is also made perceivable in a change of the signal at the coupling point. To also compensate for this change, actuation of the second function unit in operation is provided.
In particular, the second function unit, particularly the switching element of the second function unit, can hereby be controllable by a controller, wherein the controller serves to control a selection switch of the charging connection and/or the first communication device. An alternative consists of making the second function unit controllable, particularly the switching element of the second function unit, depending on a signal level detected in the transmitting communication device.
In particular, it may be provided that the second function unit is coupled for detecting the signal level of a power driver, constructed in particular as a push-pull amplifier, of the first communication device.
In another advantageous embodiment, the communications unit comprises at least a third function unit, which represents the electrical behavior of a line that connects the vehicle to the charge connector during a charging procedure. The real load of the coupling point is also hereby taken into account by the cable. In the third function unit, the cable is reproduced by concentrated, discrete elements.
Furthermore, it is advantageous if a first, a second and/or a third function unit is assigned to each of the first communication devices. In other words, this means that the compensation unit comprises a number of compensation devices corresponding to the number of charging connections, wherein each of the compensation devices preferably comprises a first, a second, and a third function unit of the type described above.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.